Daily home surveillance of arterial oxygen saturation according to pulse oximetry and weight selected patients at increased risk of interstage death, permitting timely intervention, primarily with early stage 2 palliation, and was associated with improved interstage survival. Diminished growth identified 4 to 5 months after the Norwood procedure brings into question the value of delaying stage 2 palliation beyond 5 months of age.

Cardiac MRI can predict the likely tumor type in the majority of children with a cardiac mass. A comprehensive imaging protocol is essential for accurate diagnosis. However, histologic diagnosis remains the gold standard, and in some cases malignancy cannot be definitively excluded on the basis of cardiac MRI images alone.

Eight symbiotic mutants defective in lipopolysaccharide (LPS) synthesis were isolated from Rhizobium leguminosarum biovar phaseoli CFN42. These eight strains elicited smaUl white nodules lacking infected cells when inoculated onto bean plants. The mutants had undetectable or greatly diminished amounts of the complete LPS (LPS I), whereas amounts of an LPS lacking the 0 antigen (LPS U) greatly increased. Apparent LPS bands that migrated between LPS I and LPS II on sodium dodecyl sulfate-polyacrylamide gels were detected in extracts of some of the mutants. The mutant strains were complemented to wild-type LPS I content and antigenicity by DNA from a cosmid llbrary of the wild-type genome. Most of the mutations were clustered in two genetic regions; one mutation was located in a third region. Strains complemented by DNA from two of these regions produced healthy nitrogen-fixing nodules. Strains complemented to wild-type LPS content by the other genetic region induced nodules that exhibited little or no nitrogenase activity, although nodule development was obviously enhanced by the presence of this DNA. The results support the idea that complete LPS structures, in normal amounts, are necessary for infection thread development in bean plants.Lipopolysaccharide (LPS) is found on the outer membrane of gram-negative bacteria. It consists of lipid A, which anchors it to the outer membrane, and a polysaccharide portion that extends into the cell surroundings. Besides being necessary for the structural integrity of the outer membrane, LPS molecules are likely to be involved in important interactions between the cell and its environment. LPS is proposed to protect bacterial pathogens against animal host defenses (20, 30, 35, 38). It may protect against plant defenses also. Mutants of the plant pathogen Erwinia chrysanthemi having severe LPS alterations exhibit avirulence which may have resulted from bacterial susceptibility to plant defenses (37). Strains of Pseudomonas solanacearum, another plant pathogen, are avirulent when both LPS and exopolysaccharide are altered (13).Bacteria of the genera Rhizobium and Bradyrhizobium form a nitrogen-fixing symbiosis with leguminous plants. The bacteria infect the plant roots and reside in nodules, whose development is induced by the bacteria. Various roles for rhizobial LPS in the symbiosis have been proposed.It has been suggested that LPS polysaccharides interact with the lectins of legumes (42) as a host-specific recognition step (17). Hrabak et al. (14) reported that growth-phasedependent changes occurred in the LPS composition of one strain of Rhizobium leguminosarum and that these changes may be required for recognition of the LPS by white clover. Other studies, however, have reported contradictory or mixed results concerning LPS and host-specific lectin binding (6, 16, 32). Moreover, strains that nodulate the same host can have very different LPS compositions (7). Although in at least some systems legume lectins probably do interact with LPS, such interactions are not necessari...

Early cavopulmonary anastomosis after the Norwood operation is safe. Younger patients are more cyanotic initially after surgery and have a longer duration of mechanical ventilation, pleural drainage, intensive care unit stay, and hospitalization.